The present invention relates to a door closer, and more particularly to one which has an improved mounting.
A door closer is mounted on a door for applying a torque to return the door to a closed position. Conventional mountings for door closers may be classified into three types. One is with the two end lugs which are integrally formed with the closer body, as shown in FIG. 1, and which have holes for screwing the closer body to the door. This type of mounting has the drawbacks of unsightly appearance and increasing material. Another type, as shown in FIG. 2, is that of elongated bolts passing through the closer body for screwing the closer body to the door, causing bolt-mounting part of the door to bear excessive torque. When used for a long time, it is easy to damage the bolt-mounting part. The third type, as shown in FIG. 3, includes a dovetail mounting bracket screwed to the door, and a dovetail groove formed in the closer body for engaging with the dovetail mounting bracket. The dovetail tongue and groove engagement has been disclosed in several U.S. patents, for example, U.S. Pat. Nos. 3,188,682 to M. M. Check et al., 3,252,178 to M. M. Check et al., and 4,086,681 to Nakanishi.
In M. M. Check's door closer, after the completion of engaging the dovetail tongue with the dovetail groove, to fix the closer body on the mounting bracket, the interengaging tapered surfaces between the dovetail tongue of the mounting bracket and the dovetail groove of the closer body are forced against each other by a complicated adjustment, e.g. by adjusting a cylindrical cam member with a draw bolt.
In Nakanishi's door closer, after the engagement of the dovetail tongue and the dovetail groove is completed, the closer body is secured to the mounting bracket by an elongated bolt. Then, by inserting a cover plate of a trapezoid cross-section into another dovetail groove of the closer body provided in the side remote from the mounting bracket, the head of the elongated bolt is concealed by the cover plate.
These dovetail tongues have two end surfaces which are exposed and are thus unsightly. In addition, their operation of securing the closer body to the mounting bracket is not very easy.